RALEIGH — N.C. State coach Tom O'Brien was generally pleased with his team's 43-21 win over Liberty on Saturday.

The fifth-year coach was not entirely thrilled with how the Wolfpack won, but he's not going to argue with the result.

"That's still the key," O'Brien said Monday. "After looking at college football this past weekend, some of the things that went on, you have to be happy with the victory."

O'Brien didn't mention any teams by name, but two teams from the Bowl Championship Series power structure lost to lower-level Division I opponents: Duke (to Richmond) and Oregon State (to Sacramento State).

Three other BCS programs (Iowa State, Washington and Kansas State) needed last-minute saves to hold off Football Championship Subdivision foes.

So State's 22-point win, even with issues on the offensive line and on defense, was a good way to start the season.

"It was a good challenge for us," O'Brien said. "We got pushed, but we responded and we won."

Liberty, which has won its conference four years in a row and won eight games in 2010, led 7-3 in the second quarter after the Flames scored a defensive touchdown and the Wolfpack's offense was off-balance.

Wolfpack safety Earl Wolff did a double-take when he looked at the scoreboard in the second quarter and saw the home team trailing.

"Nobody was prepared to see that," Wolff said.

Wolff stripped Liberty quarterback Mike Brown in the third quarter; defensive tackle Brian Slay picked up the ball and ran 52 yards for a touchdown to extend State's nine-point halftime lead to 23-7.

Wolff, who had an interception in the first half, accounted for two of the team's school-record seven turnovers. The coach was also pleased with the performance of Slay, who filled in for injured captain J.R. Sweezy at defensive tackle. Slay, a junior, finished with five tackles, 1.5 sacks, a forced fumble and the recovered fumble.

"He stepped up," O'Brien said. "He had his opportunity and played really well."

State needs another defensive tackle to step up because it lost backup Thomas Teal to a foot injury. Teal, a redshirt freshman, will be out four to six weeks, O'Brien said. Teal injured his foot on a sack in the third quarter, the same injury and had the same surgery as Sweezy - who broke a bone in his left foot during training camp.

The loss leaves State with four healthy defensive tackles for this week's ACC opener at Wake Forest. Freshman T.Y. McGill is listed as the backup to Slay in the depth chart. Markus Kuhn and A.J. Ferguson are the other healthy tackles.

O'Brien pointed out the defense gave up too many big plays in the third quarter and the offensive line needed to do a better job protecting quarterback Mike Glennon, who was sacked four times.

He also said his freshman kickers "survived" their college debut. In all, though, the players know they can get better.

"It was a good learning game," tight end George Bryan said.

jp.giglio@newsobserver.com or 919-829-8938